Safety device for elevators.



I. L. DAVIS.

SAFETY DEVICE FOR ELEVATORS.

APPLICATION FILED APR. 19, I916.

Patented May 15, 1917.

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JOHN L. DAVIS, 01? \VALNUT SPRINGS, TEXAS.

SAFETY DEVICE FOR ELEVATORS.

Specification of Letters Patent.

Patented May 15, 1917.

AppIication filed April 19, 1916. 'Serial No. 92,271.

To all whom it may concern:

Be it known that I, JOHN L. DAVIS, a citizen of the United States, residing at Walnut Springs, in the county of Bosque and State of Texas, have invented certain new and useful Improvements in Safety Devices for Elevators, of which the following is a specification, reference being had to the accompanying drawings.

This invention relates to an improved safety device for elevators and has for its primary object to provide simple and effective means for automatically bringing the elevator to a gradual stop in its descent when the cable breaks or, for any reason, the engine becomes uncontrollable or inoperative.

It is another and more particular object of the invention to provide a device of the above character, including pivotally mounted brake shoes, mechanism for holding the brake shoes in their inoperative positions and embodying a latch element, a counterbalanced fan blade operatively connected to the latch element to move the same upon the sudden descent of the elevator cage and release said mechanism, and means for actuating the mechanism upon its release to frictionally engage the brake shoes with the ver tical guide rails.

It is another general object of the invention to provide a brake mechanism for elcvatorsp which is simple and durable in its construction, and may be installed in the elevator at relatively small cost.

WVith the above and other objects in view, my invention consists in the novel features of construction, combination and arrangement of parts to be hereinafter more fully described, claimed and illustrated in the accompanying drawing, in which,

Figure l is a side elevation showing the mechanism in set position during the normal operation of the elevator;

Fig. 2 is a similar view showing the relative positions of the parts when the brake shoes have been released and frictionally engaged with the guide rails;

Fig. 3 is a sectional view taken on the line 3-3 of Fig. 2; and

Fig. 4 is a horizontal section taken on the line l4: of Fig. 2.

Referring in detail to the drawing, 5 designates the elevator car or cage which is mounted in any ordinary or approved manner for vertical movement between the guide rails 6 which are suitably secured to the opupon which the upper end of a lever 12 is fulcrumed. This lever extends downwardly through an opening indicated at 13, in the beam 7 on the top wall of the elevator cage, and to the lower end of the lever a coil spring 14 is attached at one of its ends. This spring yieldingly holds the lever against movement in one direction. T o the lever 12, on relatively opposite sides of the pivot bolt 11, the inner ends of the bars 15 are pivotally connected, the outer ends of said bars being connected to the upper ends of the respective brake shoes 8.

Upon the beam 7 adjacent one of its ends, spaced standards 16 are securely mounted, and between the upper ends of said standards the central rod 17 of the fan blade 18, is fulcrumed for rocking or pivotal movement adjacent one of its ends. This end of said rod is threaded to receive an adjustable counterbalancing weight 19 which normally acts to hold the fan blade in an upwardly inclined or elevated position.

A single vertical standard or post 20 is also mounted upon the beam 7 on the opposite side of the lever 12 with respect to the standards 16, and upon the upper end of this standard 20 the latch bar 21 is pivotally mounted at one of its ends. This bar is longitudinally slotted, as at 22, and in said slot a roller 23 is mounted upon a transverse axle pin 24:- The upper end of the lever 12 is adapted to extend upwardly into the slot in said latch lever for engagement against one side of said roller. A wire link or loop 25 connects the other end of the latch lever to the central rod 17 of the fan 18 adjacent to the pivot or fulcrum of said rod.

From the above description, the construction, manner of operation, and several advantages of the device will be clearly understood. When the parts are arranged in set position as shown in Fig. 1, the fan blade 18 is disposed in a substantially horizontal position and the upper end of the lever 12 is disposed in the slot of the latch bar 21 and against the right hand side of the roller 23 therein. In order to dispose the upper end of the lever in this position, the lower end thereof must be moved to the left, thereby placing the spring 14 under tension. The fan blade 18 is of only slightly less width than the width of the elevator shaft, and this blade is provided with an opening indicated at 26, through which the air may freely pass in the normal operation of the elevator. Should the hoisting cable break, or the engine become inoperative for any reason, upon the sudden descent of the car or cage a heavy pressure of air will result against the under side of the fan blade 18 and force the same upwardly so that the loop connection 25 will act against the end of the latch bar 21 to raise the same and disengage the roller 23 from the upper end of the lever 12. The counterbalancing weight 19 will accelerate the movement of the fan blade immediately upon the upward movement of the same from its horizontal position induced by the sudden and heavy pressure of air against said blade. The spring 14 will then immediately contract to move the lever 12 and shift the connecting bars 15 in relatively opposite directions, thereby forcing the upper ends of the brake shoes 8 outwardly and frictionally engaging the brake shoes against the vertical guide rails 6 of the elevator. Thus, the descent of the car or cage will be checked, and not suddenly or abruptly stopped, in which latter event the passengers might suffer probable injuries. The speed of the elevator cage is, however, appreciably lessened and the frictional pressure of the brake shoes against the rails may be increased or decreased by the operator exerting pressure against the lower end of the lever 12, as will be readily understood, until the cage is finally brought to a gradual stop.

It will be seen from the above description, that I have produced an exceedingly simple and effective automatically operating brake or safety device for elevators which is reliable and positive in its action and can also be manufactured and installed upon the ordinary type of elevator now in general use at comparatively small cost. By means of the invention, the possibility of severe injuries to passengers in the elevator car is reduced to a minimum. The several cooperating elements of the device may, of course, be greatly modified in form, proportion and arrangement, and I, therefore, reserve the privilege of adopting all such legitimate changes as may be fairly embodied within the spirit and scope of the invention as claimed.

Having thus fully described my invention, what I desire to claim and secure by Letters Patent is The combination with an elevator car and vertical guide rails therefor, of a vertically disposed lever pivotally mounted upon the top of the car, pivotally mounted brake shoes to engage the respective guide rails, links operatively connecting said shoes to the lever on relatively opposite sides of its pivot, a latch bar pivotally mounted at one of its ends upon the top of the car and provided with a slot in which the upper end of the pivoted lever is engaged, a roller mounted in said slot, a spring connected to the lower end of the lever and holding said lever at its upper end in bearing engagement against the roller, a counterbalanced fan blade pivotally mounted upon the top of the car at one of its ends, and a link connection between said blade, adjacent to its pivoted end, and the other end of the latch bar, whereby said bar is actuated in the upward movement of the fan blade when subjected to excessive air pressure to permit of the movement of said lever under the action of the spring and the frictional engagement of the brake shoes with the guide rails. 1

In testimony whereof I hereunto aflix my signature in presence of two witnesses.

JOHN L. DAVIS. Witnesses:

J. A. COLE, F. V. GATES,

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents, Washington, D. 0. 

